1. Field of the Invention
The present invention relates to a recording medium having a data structure for managing reproduction of at least multiple graphics streams recorded thereon as well as methods and apparatuses for reproduction and recording.
2. Description of the Related Art
An optical disc such as a DVD (Digital Versatile Disc), capable of recording high quality video and audio data for many hours, is being developed and released to consumer markets. Various types of DVD exist including DVD-ROM and DVD-RW (DVD-Rewritable).
Video and audio streams in a DVD-ROM are recorded in units of a program stream packet defined by the MPEG standard. As shown in FIG. 1, one pack corresponds to a single physical sector with the record size of 2048 bytes.
A single pack is composed of a pack header and includes packets of video, audio, and sub-pictures. The pack header includes pack start code (Pack_start_code), SCR, program mux rate (program_mux_rate), and stuffing length (Stuffing_length).
In a DVD-ROM where a single physical sector corresponds to a single pack in the above-described manner, multiple audio streams may be recorded in a number of respective coding formats in a data area of the DVD-ROM.
As shown in FIG. 2, an optical disc apparatus such as a DVD player may comprise an optical pickup 111, a VDP (Video Disc Play) system 112, a D/A converter 113. The VDP system 112 may comprise a PS DEMUX 120 and a decoding block 121.
The VDP system 112 reads out and plays video and audio streams recorded in the DVD-ROM 110 in units of a program stream packet. The PS DEMUX 120 may output, for example, subtitle data, recorded with main video and audio streams in a part of data area of said DVD-ROM, to the decoding block 121 by demultiplexing in units of a PES (Packetized Elementary Stream).
The decoding block 121 then performs a series of decoding operations on the subtitle data of packetized elementary streams received from the PS DEMUX 120 in order for the subtitle data to be displayed together with the main video, e.g., as a caption overlay.
Accordingly, a user can watch the caption overlay of the subtitle data together with the main video frame.
Recently, standardization of high-density optical discs such as a read-only Blu-ray disc (BD-ROM), which has a higher recording capacity than a DVD, is underway. However, an appropriate method for managing multiple graphics streams for the high-density optical disc has not been established.